Special-shaped pole piece, winding type battery cell and lithium ion battery

Abstract

The utility model provides a special-shaped pole piece, a winding type battery cell and a lithium ion battery, and relates to the technical field of lithium ion batteries, the special-shaped pole piece comprises a pole piece main body and active substance layers coated on two sides of the pole piece main body, and one end of an outer active substance layer and one end of an inner active substance layer in the width direction of the pole piece main body are flush; the width of the inner active material layer is larger than that of the outer active material layer. The two sides of the pole piece main body of the special-shaped pole piece provided by the utility model are coated with the active substance layers, and the width of the outer active substance layer of the active substance layers is smaller than that of the inner active substance layer; when the special-shaped pole piece is wound into a battery cell, the pole piece main body with the outer active material layer is positioned on the outer side of the battery cell; when the cover plate assembly is welded with the shell, the diaphragm shrinks, and no outer active material layer is arranged on the two sides of the diaphragm, so that contact between the cathode and the anode is avoided, and short circuit is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium ion batteries, in particular to a special-shaped pole piece, a winding type battery core and a lithium ion battery. Background Art

[0002] In recent years, with the rise of wearable products, the demand for miniaturization, diversification, and long battery life of battery products has become increasingly obvious; this requires that while ensuring product performance, the actual internal utilization space of battery products should be increased as much as possible, thereby increasing energy density.

[0003] Steel shell button battery, also known as button battery, refers to a battery with a button-like appearance. Steel shell button battery generally includes the following two sealing forms; one is to seal the battery shell and shell cover with a sealing rubber ring. In this form, the sealing rubber ring is prone to aging and affects the sealing performance, and the available space in the shell is small. The other is composed of a cover plate assembly and an outer shell. The cover plate assembly includes a cover sheet. The cover sheet and the outer shell are welded to form a battery shell with the cover plate assembly and the outer shell. The winding core is located in the battery shell. The battery shell is a sealed structure and has good sealing stability and available space inside the shell. However, during the welding process, the laser beam irradiates the surface of the outer shell material and absorbs energy. The temperature rises rapidly to the melting point. The heat generated can easily burn the diaphragm, causing shrinkage, causing the anode and cathode to contact and cause a short circuit. Utility Model Content

[0004] The utility model aims to provide a special-shaped pole piece, a wound battery cell and a lithium-ion battery, so as to alleviate the technical problem in the prior art that when the cover plate assembly is welded to the shell, the diaphragm is easily burned, the diaphragm shrinks, and the cathode and anode contact and cause a short circuit.

[0005] The utility model provides a special-shaped pole piece, comprising a pole piece body and active material layers coated on both sides of the pole piece body, wherein the active material layers include an outer active material layer and an inner active material layer sequentially arranged along the length direction of the pole piece body; and the outer active material layer and the inner active material layer are flush at one end in the width direction of the pole piece body;

[0006] The width of the inner active material layer is greater than the width of the outer active material layer.

[0007] In an optional embodiment, the length of the outer active substance layer is 20 mm, and the length of the inner active substance layer is 480 mm;

[0008] The width of the outer active material layer is 4.5 mm, and the width of the inner active material layer is 5.0 mm.

[0009] In an optional embodiment, the width of the inner active material layer is greater than the width of the outer active material layer by more than 0.2 mm.

[0010] In an optional embodiment, the width of the outer active material layer gradually decreases in a direction away from the inner active material layer.

[0011] The utility model provides a special-shaped pole piece, both sides of which are coated with active material layers, the width of the outer active material layer of the active material layer is smaller than the width of the inner active material layer; when the special-shaped pole piece is wound into a battery cell, the pole piece body with the outer active material layer is located on the outside of the battery cell; when the cover plate assembly is welded to the shell, the diaphragm is caused to shrink, and there is no outer active material layer on both sides of the diaphragm, thereby avoiding contact between the cathode and the anode and avoiding short circuit.

[0012] The utility model also provides a wound battery cell, comprising a battery cell body, wherein the battery cell body comprises an anode sheet, a cathode sheet and a separator arranged between the anode sheet and the cathode sheet; the battery cell body is formed by winding the anode sheet, the separator and the cathode sheet;

[0013] The anode sheet and / or the cathode sheet adopts the special-shaped electrode sheet described in any one of the aforementioned embodiments.

[0014] Compared with the prior art, the wound battery core provided by the utility model has the special-shaped pole piece provided by the utility model, and thus has all the beneficial effects of the special-shaped pole piece provided by the utility model.

[0015] The utility model also provides a lithium ion battery, comprising the wound battery core described in the above embodiment.

[0016] In an optional embodiment, it further includes a cover plate assembly and a shell; the shell has an upper opening, the wound battery cell is arranged in the shell, and the cover plate assembly is arranged at the upper opening and welded to the shell.

[0017] In an optional embodiment, a negative electrode tab is provided on the wound battery cell, and the negative electrode tab is connected to the bottom of the shell after being bent.

[0018] In an optional embodiment, a positive electrode tab is provided on the wound battery cell, and one end of the positive electrode tab is connected to the cover plate assembly.

[0019] In an optional embodiment, the cover plate assembly includes a cover plate body and a positive electrode post disposed on the cover plate body; the positive electrode tab is connected to the positive electrode post.

[0020] Compared with the prior art, the lithium-ion battery provided by the utility model has the wound-type battery core provided by the utility model, and thus has all the beneficial effects of the wound-type battery core provided by the utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the structure of a special-shaped pole piece provided in an embodiment of the utility model;

[0023] Figure 2 for Figure 1 A schematic structural diagram of the special-shaped pole piece from another angle shown;

[0024] Figure 3 for Figure 1 Another structural schematic diagram of the special-shaped pole piece shown;

[0025] Figure 4 An exploded diagram of a lithium-ion battery provided in an embodiment of the utility model.

[0026] Icon: 100-pole body; 200-active material layer; 201-external active material layer; 202-inner active material layer; 300-negative electrode tab; 400-shell; 500-cell body; 600-cover assembly; 700-positive electrode tab. DETAILED DESCRIPTION

[0027] The terms “first”, “second”, “third”, etc. are only used for distinguishing descriptions and do not indicate the order of arrangement, nor can they be understood as indicating or implying relative importance.

[0028] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0029] In the description of the present application, it should be noted that the terms "inside", "outside", "left", "right", "up", "down", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the products of the present application are usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0030] In the description of this application, unless otherwise clearly specified and limited, the terms "set", "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0031] The technical solution of the present application will be described clearly and completely below in conjunction with the accompanying drawings.

[0032] Example

[0033] Reference Figure 1-Figure 3 The utility model provides a special-shaped pole piece, comprising a pole piece body 100, and an active material layer 200 coated on both sides of the pole piece body 100, wherein the active material layer 200 comprises an outer active material layer 201 and an inner active material layer 202 sequentially arranged along the length direction of the pole piece body 100; and the outer active material layer 201 and the inner active material layer 202 are flush at one end in the width direction of the pole piece body 100;

[0034] The width of the inner active material layer 202 is greater than the width of the outer active material layer 201 .

[0035] In some embodiments, both sides of the pole piece body 100 of the special-shaped pole piece are coated with an active material layer 200, and the active material layer 200 includes an outer active material layer 201 and an inner active material layer 202; when the special-shaped pole piece is wound into a battery cell, the special-shaped pole piece with the inner active material layer 202 is wound first; that is, the outermost side of the battery cell is the special-shaped pole piece with the outer active material layer 201.

[0036] The outer active material layer 201 and the inner active material layer 202 are flush at one end of the electrode body 100 in the width direction; the inner active material layer 202 protrudes from the outer active material layer 201 at the other end; there is no outer active material layer 201 on both sides of the outermost part of the diaphragm of the battery cell formed in this way; that is, when the outermost diaphragm of the battery cell shrinks due to heat, it will not cause contact between two adjacent special-shaped electrodes.

[0037] In an optional embodiment, the length of the outer active material layer 201 is 20 mm, and the length of the inner active material layer 202 is 480 mm;

[0038] The width of the outer active material layer 201 is 4.5 mm, and the width of the inner active material layer 202 is 5.0 mm.

[0039] In an optional embodiment, the width of the inner active material layer 202 is greater than the width of the outer active material layer 201 by more than 0.2 mm.

[0040] Reference Figure 3 In an optional embodiment, the width of the outer active material layer 201 gradually decreases in a direction away from the inner active material layer 202 .

[0041] In some embodiments, the length of the outer active material layer 201 is generally 20 mm, while the length of the inner active material layer 202 is 480 mm. The length of the outer active material layer 201 is adjusted according to the size of the battery cell, and it is necessary to ensure that at least the outermost circle of the special-shaped pole pieces of the battery cell have the outer active material layer 201.

[0042] In order to further improve the safety of the battery cell, the width of the outer active material layer 201 gradually decreases; when the cover plate assembly 600 and the shell 400 are welded, the closer the diaphragm is to the inner wall of the shell 400, the more heat it receives and the more severe the degree of shrinkage of the diaphragm. According to this feature, the width of the outer active material layer 201 gradually decreases, that is, the distance between the upper end of the outer active material layer 201 and the cover plate assembly 600 gradually decreases in the direction from the inner wall of the shell 400 to the center of the shell 400.

[0043] The special-shaped pole piece can be used as a cathode pole piece or an anode pole piece. When the special-shaped pole piece is used as a cathode pole piece, the pole piece body 100 is a copper foil current collector, and cathode material, adhesive, conductive agent and aqueous or oily solvent, etc., i.e., active material layer 200, are coated on the copper foil current collector.

[0044] When the special-shaped pole piece is used as an anode pole piece, the pole piece body 100 is an aluminum foil current collector coated with anode material, adhesive, conductive agent and oily solvent, that is, an active material layer 200. The components of the active material layer 200 are the existing technology.

[0045] The pole piece body 100 of the special-shaped pole piece provided by the utility model is coated with active material layers 200 on both sides, and the width of the outer active material layer 201 of the active material layer 200 is smaller than the width of the inner active material layer 202; when the special-shaped pole piece is wound into a battery cell, the pole piece body 100 with the outer active material layer 201 is located on the outside of the battery cell; when the cover plate assembly 600 is welded to the shell 400, the diaphragm is caused to shrink, and there is no outer active material layer 201 on both sides of the diaphragm, which avoids contact between the cathode and the anode and avoids short circuit.

[0046] The utility model also provides a wound battery cell, comprising a battery cell body 500, wherein the battery cell body 500 comprises an anode sheet, a cathode sheet, and a separator disposed between the anode sheet and the cathode sheet; the battery cell body 500 is formed by winding the anode sheet, the separator, and the cathode sheet;

[0047] The anode sheet and / or the cathode sheet adopts the special-shaped electrode sheet described in any one of the aforementioned embodiments.

[0048] The special-shaped pole piece structure can effectively avoid the high temperature influence generated by the laser melting shell 400 and the cover plate assembly 600 during laser welding. The anode piece and the cathode piece will not contact due to diaphragm burns, and the battery energy density and safety performance are greatly improved.

[0049] The battery cell body 500 is composed of an anode sheet, a separator, a cathode sheet and a separator winding; the outermost side of the battery cell body 500 is the separator, and the cathode sheet and the anode sheet will not contact each other even if the separator shrinks due to heat; but after the separator on the inner side of the outermost special-shaped electrode sheet shrinks due to heat, the width of the outer active material layer 201 of the outermost adjacent cathode sheet and anode sheet is narrower than the width of the inner active material layer 202, and there is no outer active material layer 201 on both sides of the shrunk separator here, thereby effectively avoiding the short circuit between the cathode sheet and the anode sheet.

[0050] Reference Figure 4 The utility model also provides a lithium-ion battery, comprising the wound battery cell described in the aforementioned embodiment.

[0051] In an optional embodiment, a cover plate assembly 600 and a shell 400 are further included; the shell 400 has an upper opening, the wound battery cell is arranged in the shell 400, and the cover plate assembly 600 is arranged at the upper opening and welded to the shell 400.

[0052] In an optional embodiment, a negative electrode tab 300 is provided on the wound battery cell, and the negative electrode tab 300 is connected to the bottom of the shell 400 after being bent.

[0053] In an optional embodiment, a positive electrode tab 700 is provided on the wound battery cell, and one end of the positive electrode tab 700 is connected to the cover plate assembly 600 .

[0054] In an optional embodiment, the cover plate assembly 600 includes a cover plate body and a positive electrode column disposed on the cover plate body; the positive electrode tab 700 is connected to the positive electrode column.

[0055] The cover plate assembly 600 includes a cover plate body and a positive electrode column disposed on the cover plate body. The positive electrode tab 700 of the wound battery cell is connected to the positive electrode column, and the negative electrode tab 300 on the wound battery cell is connected to the bottom of the shell 400.

[0056] When the wound battery cell is assembled into the shell 400 from the upper opening of the shell 400, the flush ends of the outer active material layer 201 and the inner active material layer 202 face the bottom of the shell 400, and in the height direction of the shell 400, the upper end of the outer active material layer 201 is lower than the upper end of the inner active material layer 202.

[0057] When the cover plate assembly 600 and the shell 400 are laser welded, during the welding process, the laser beam is irradiated to the surface of the shell 400 material. After absorbing energy, the temperature rises rapidly to the melting point. The heat generated can easily burn the diaphragm, causing the diaphragm to shrink, causing the anode and cathode sheets to contact and cause a short circuit, thereby reducing the safety of the lithium-ion battery.

[0058] The active material layer 200 of the outermost special-shaped pole piece of the wound battery cell is an outer active material layer 201, and there is a certain distance between the outer active material layer 201 and the cover plate assembly 600. This ensures that after the diaphragm shrinks, the cathode sheet and the anode sheet at the shrinking point of the diaphragm have no active material layer 200, that is, the anode sheet and the cathode sheet will not short-circuit, thereby improving the safety of the lithium-ion battery.

[0059] It is not only beneficial to improve the yield rate of button batteries, but also beneficial to ensure the quality and performance of button steel shell batteries.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

Claims

1. A special-shaped pole piece, characterized in that: The invention comprises a pole piece body (100) and active material layers (200) coated on both sides of the pole piece body (100), wherein the active material layer (200) comprises an outer active material layer (201) and an inner active material layer (202) sequentially arranged along the length direction of the pole piece body (100); and one end of the outer active material layer (201) and the inner active material layer (202) in the width direction of the pole piece body (100) are flush; The width of the inner active material layer (202) is greater than the width of the outer active material layer (201).

2. The special-shaped pole piece according to claim 1, characterized in that: The length of the outer active material layer (201) is 20 mm, and the length of the inner active material layer (202) is 480 mm; The width of the outer active material layer (201) is 4.5 mm, and the width of the inner active material layer (202) is 5.0 mm.

3. The special-shaped pole piece according to claim 1, characterized in that: The width of the inner active material layer (202) is greater than the width of the outer active material layer (201) by at least 0.2 mm.

4. The special-shaped pole piece according to claim 1, characterized in that: The width of the outer active material layer (201) gradually decreases in a direction away from the inner active material layer (202).

5. A wound battery cell, characterized in that: The battery cell body (500) comprises an anode sheet, a cathode sheet and a separator arranged between the anode sheet and the cathode sheet; the battery cell body (500) is formed by winding the anode sheet, the separator and the cathode sheet; The anode sheet and / or the cathode sheet adopts the special-shaped electrode sheet described in any one of claims 1-4.

6. A lithium ion battery, characterized in that: Including the wound battery cell as described in claim 5.

7. The lithium-ion battery according to claim 6, characterized in that: It also includes a cover plate assembly (600) and a shell (400); the shell (400) has an upper opening, the wound battery core is arranged in the shell (400), and the cover plate assembly (600) is arranged at the upper opening and welded to the shell (400).

8. The lithium-ion battery according to claim 7, characterized in that: The wound battery cell is provided with a negative electrode tab (300), and the negative electrode tab (300) is connected to the bottom of the shell (400) after being bent.

9. The lithium-ion battery according to claim 7, characterized in that: The wound battery cell is provided with a positive electrode tab (700), and one end of the positive electrode tab (700) is connected to the cover plate assembly (600).

10. The lithium ion battery according to claim 9, characterized in that: The cover plate assembly (600) comprises a cover plate body and a positive electrode column arranged on the cover plate body; the positive electrode tab (700) is connected to the positive electrode column.

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